This invention relates to a valve adaptor for a disc valve assembly to provide enhanced sealing action, and more particularly, to a rising disc valve or similar unit.
A rising disc valve assembly is commercially available and comprises a housing having a bore and a frusto-conical valve seat at one end of the bore. A handle is attached to a stem which is threaded to the housing bore for axially displacing the stem in the bore. A steel disc valve member with a frustoconical portion mates with and seats in the housing valve seat as the handle and stem are rotated. In the alternative, instead of a hard steel disc valve member the assembly may have what is referred to as a soft seal which may be thermoplastic material or other resilient material which engages a mating housing valve seat. However, in either.case, once the seal breaks down and leaks, the seal needs to be immediately replaced. The metal to metal disc seal tends to break down relatively quickly due to scratches and wear and so on. When the soft seal breaks down this seal also needs to be replaced at that time.
U.S. Pat. No. 2,918,078 discloses a valve having clamped valve member resilient insert and a resilient valve member seat insert. As the valve is closed one insert engages the other insert and the opposed sealing surfaces form an initial seal. Further movement of the valve member moves a pressure plate which engages projections and ribs which limit the downward movement. Further downward movement of the valve member body effects a further clamping of the valve member insert and expansion of the peripheral part thereof beyond the valve member body to increase the seal between the valve member insert and the valve seat insert.
U.S. Pat. No. 3,211,418 discloses a shut off valve comprising a spindle that can move a distance without displacing a piston coupled thereto. A nut is attached to the spindle for compressing a set of flat washer-like spring against a piston cap. The piston has a body that carries an elastically compressible sealing ring. The piston cap transmit pressure from the spring to the sealing ring. The sealing ring is constantly subject to axial elastic pressure of the springs. The outside surface of the sealing ring and piston body are a frustum of a cone and mate with a conical bore of the housing. Downward movement of the spindle seats the piston on the housing bore. Continued downward movement of the spindle causes it to displace relative to the piston body compressing the springs. This exerts a higher pressure on the sealing ring to more tightly seat it against the housing conical bore.
The springs thus urge both the sealing ring and the piston into sealing engagement by compression of the springs by the nut on the spindle as the spindle is moved downward relative to the piston. The spindle is otherwise loosely coupled to the sealing ring and piston and does not directly move the piston. Failure of the springs will release both the sealing ring and the piston from their sealed engagement with the housing bore. This is not desirable.
U.S. Pat. No. 2,574,054 discloses an aircraft brake system in which pressurized fluid is used to compress a compressible ring seal to provide sealing action.
The present inventor recognizes a need for a valve structure that solves the problems of the above and has longer life than the present seals described above. A need is seen for a fail safe valve that remains closed in case of valve failure. Further, a need is seen for a valve adaptor that is easily interchangeable and replaceable with the valve stem in the field to replace worn seals at relatively low cost.
A valve adaptor according to the present invention is for use with a disc valve arrangement including a housing having a valve seat in communication with a cylindrical bore in which a valve stem is located for axial displacement of the valve arrangement, the housing including first abutment means in the bore. The adaptor comprises a shank. A first relatively rigid incompressible valve member is secured to the shank for selectively engaging the valve seat to form a first seal in a closed state. A second resilient valve member is movably attached to the shank and has opposite sides for compressively distorting in response to an applied load to form a second seal with the bore. At least one resilient member is coupled to and between the first and second valve members. Second abutment means are on a side of the second valve member opposite the at least one resilient member for abutting the housing first abutment means and for limiting the displacement of the second valve member in the bore as the first valve member and shank are displaced to the closed state such that the displacement of the first valve member to the closed state displaces the first valve member relative to the second valve member and compresses the at least one resilient member to apply the load to the second valve member prior to the closing of the first valve member. An attachment member secures the shank to the stem.
In a further aspect, the at least one resilient member comprises at least one washer-like spring.
In a further aspect, the at least one resilient member comprises a stack of Belleville springs.
In a further aspect, the Belleville springs each comprise sheet steel having a convex outer surface and a complementary concave inner surface, the stack comprising a first spring having its concave surface facing in a direction toward the second valve member and a second spring having its concave surface facing in a direction toward the first valve member.
In a still further aspect, the adaptor:includes an interface member between the second valve member and the first spring, the first spring abutting the interface member and the interface member abutting the second valve member.
In a further aspect, the first valve member is steel and the second valve member is thermoplastic.
In a further aspect, the second valve member is polytetraflouride.
In a further aspect, the second valve member is a cylindrical ring.
In a further aspect, the attachment member is arranged for releasably engaging the stem and releasably securing the resilient member, and the first and second valve members thereto.
In a further aspect, the means for releasably securing includes a piston member secured to the first and second valve members, the second valve member for sealing engaging the piston member in response to the compressive distorting.
in a further aspect, a spring arrangement is coupled to the first and second valve members for providing the applied load in response to the selective engagement of the first valve member.
In a further aspect, the spring arrangement comprises a stack of Belleville springs coupled between the first and second valve members.
In a still further aspect, the Belleville springs each comprise sheet steel having a convex outer surface and a complementary concave inner surface, the stack comprising a first spring having its concave surface facing in a direction toward the second valve member and a second spring having its concave surface facing in a direction toward the first valve member.
In a further aspect, an interface member is between the second valve member and the first spring, the first spring abutting the interface member and the interface member abutting the second valve member.
In a still further aspect, the first valve member is steel and the second valve member is plastic and preferably the second valve member is Teflon, and more preferably, the second valve member is a cylindrical ring.
In a further aspect, an interface arrangement is for releasing engaging the stem and releasably securing the first and valve members thereto.
In a further aspect, the springs are arranged for displacing about 0.05 inches in response to about a one thousand pound load.